This application claims the benefit of Japanese Application No. 2002-114817 filed Apr. 17, 2002.
The present invention relates to an RF (radio frequency) coil, RF signal transmitting/receiving apparatus, RF signal receiving apparatus, and magnetic resonance imaging apparatus, and more particularly to an RF coil, RF signal transmitting/receiving apparatus, RF signal receiving apparatus, and magnetic resonance imaging apparatus for use in magnetic resonance imaging of the lower abdomen of a human body.
In a magnetic resonance imaging (MRI) apparatus, a subject to be imaged is carried into an internal space of a magnet system, i.e., an imaging space in which a static magnetic field is generated, a gradient magnetic field and a high frequency magnetic field are applied to generate a magnetic resonance signal by spins within the subject, and an image is reconstructed based on the received signal.
The high frequency magnetic field is applied as an RF pulse. The application of the RF pulse is sometimes referred to as transmission of an RF signal. The magnetic resonance signal is received as an RF signal. The RF signals are transmitted and received using an RF coil.
RF coils include one dedicated for transmission or reception, and one used both for transmission and reception. For the RF coil dedicated for reception or that used both for transmission and reception, various shapes of the RF coil are available depending upon a region to be imaged. One of such RF coils is an RF coil for imaging the prostate. This RF coil is a saddle coil having a geometry such that it sandwiches the lower abdomen of the subject from the anterior and posterior sides.
Since the prostate lies in the lowest portion of the lower abdomen, an image cannot always be obtained with a sufficiently good SNR (signal-to-noise ratio) even if such an RF coil is employed.
It is therefore an object of the present invention to provide an RF coil, RF signal transmitting/receiving apparatus, RF signal receiving apparatus, and magnetic resonance imaging apparatus that enable proper imaging of the prostate.
(1) The present invention, in accordance with one aspect thereof for solving the aforementioned problem, is an RF coil characterized in comprising: a first saddle coil having two loop portions of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loop portions facing each other; and a second saddle coil having two loop portions of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loop portions, and sandwiching the lower abdomen from the right and left sides with the two loop portions facing each other.
(2) The present invention, in accordance with another aspect thereof for solving the aforementioned problem, is an RF signal transmitting/receiving apparatus characterized in comprising: a first saddle coil having two loop portions of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loop portions facing each other; a second saddle coil having two loop portions of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loop portions, and sandwiching the lower abdomen from the right and left sides with the two loop portions facing each other; driving means for driving said first and second saddle coils in a quadrature scheme; and combining means for combining two RF signals respectively received by said first and second saddle coils in a quadrature scheme.
(3) The present invention, in accordance with still another aspect thereof for solving the aforementioned problem, is an RF signal receiving apparatus characterized in comprising: a first saddle coil having two loop portions of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loop portions facing each other; a second saddle coil having two loop portions of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loop portions, and sandwiching the lower abdomen from the right and left sides with the two loop portions facing each other; and combining means for combining two RF signals respectively received by said first and second saddle coils in a quadrature scheme.
(4) The present invention, in accordance with still another aspect thereof for solving the aforementioned problem, is an RF signal receiving apparatus characterized in comprising: a first saddle coil having two loop portions of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loop portions facing each other; a second saddle coil having two loop portions of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loop portions, and sandwiching the lower abdomen from the right and left sides with the two loop portions facing each other; and combining means for combining two RF signals respectively received by said first and second saddle coils in a phased-array scheme.
(5) The present invention, in accordance with still another aspect thereof for solving the aforementioned problem, is a magnetic resonance imaging apparatus having static magnetic field generating means for generating a static magnetic field in a space for accommodating a subject to be imaged, gradient magnetic field generating means for generating a gradient magnetic field in said space, RF signal receiving means for transmitting an RF signal to said space and receiving an RF signal from said space, and image producing means for producing an image based on said received RF signal, characterized in that: said RF signal transmitting/receiving means comprises a first saddle coil having two loop portions of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loop portions facing each other; a second saddle coil having two loop portions of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loop portions, and sandwiching the lower abdomen from the right and left sides with the two loop portions facing each other; driving means for driving said first and second saddle coils in a quadrature scheme; and combining means for combining two RF signals respectively received by said first and second saddle coils in a quadrature scheme.
(6) The present invention, in accordance with still another aspect thereof for solving the aforementioned problem, is a magnetic resonance imaging apparatus having static magnetic field generating means for generating a static magnetic field in a space for accommodating a subject to be imaged, gradient magnetic field generating means for generating a gradient magnetic field in said space, RF signal transmitting means for transmitting an RF signal to said space, RF signal receiving means for receiving an RF signal from said space, and image producing means for producing an image based on said received RF signal, characterized in that: said RF signal receiving means comprises a first saddle coil having two loop portions of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loop portions facing each other; a second saddle coil having two loop portions of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loop portions, and sandwiching the lower abdomen from the right and left sides with the two loop portions facing each other; and combining means for combining two RF signals respectively received by said first and second saddle coils in a quadrature scheme.
(7) The present invention, in accordance with still another aspect thereof for solving the aforementioned problem, is a magnetic resonance imaging apparatus having static magnetic field generating means for generating a static magnetic field in a space for accommodating a subject to be imaged, gradient magnetic field generating means for generating a gradient magnetic field in said space, RF signal transmitting means for transmitting an RF signal to said space, RF signal receiving means for receiving an RF signal from said space, and image producing means, for producing an image based on said received RF signal, characterized in that: said RF signal receiving means comprises a first saddle coil having two loop portions of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loop portions facing each other; a second saddle coil having two loop portions of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loop portions, and sandwiching the lower abdomen from the right and left sides with the two loop portions facing each other; and combining means for combining two RF signals respectively received by said first and second saddle coils in a phased-array scheme.
In the invention of the aspects described in (1)-(7), an RF coil comprises a first saddle coil having two loop portions of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loop portions facing each other, and a second saddle coil having two loop portions of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loop portions, and sandwiching the lower abdomen from the right and left sides with the two loop portions facing each other, so that magnetic resonance signals from the prostate portion can be received with a good SNR.
In the RF coil, said two loops in said second saddle coil preferably have a geometry, such that the two loops are made partially close to and facing each other along a medial line of said human body so that high-sensitivity regions in the first and second saddle coils coincide with each other.
The RF coil preferably comprises a flexible substrate having a geometry suited for being fitted over the lower abdomen of the human body, for supporting circuit patterns of said first and second saddle coils, so that fitting on the human body is improved.
(8) The present invention, in accordance with still another aspect thereof for solving the aforementioned problem, is an RF coil characterized in comprising: a first coil pair comprised of two loops of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loops facing each other; and a second coil pair comprised of two loops of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loops, and sandwiching the lower abdomen from the right and left sides with the two loops facing each other.
(9) The present invention, in accordance with still another aspect thereof for solving the aforementioned problem, is an RF signal receiving apparatus characterized in comprising: a first coil pair comprised of two loops of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loops facing each other; a second coil pair comprised of two loops of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loops, and sandwiching the lower abdomen from the right and left sides with the two loops facing each other; and combining means for combining two RF signals respectively received by said first and second coil pairs in a phased-array scheme.
(10) The present invention, in accordance with still another aspect thereof for solving the aforementioned problem, is a magnetic resonance imaging apparatus having static magnetic field generating means for generating a static magnetic field in a space for accommodating a subject to be imaged, gradient magnetic field generating means for generating a gradient magnetic field in said space, RF signal transmitting means for transmitting an RF signal to said space, RF signal receiving means for receiving an RF signal from said space, and image producing means for producing an image based on said received RF signal, characterized in that: said RF signal receiving means comprises a first coil pair comprised of two loops of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loops facing each other; a second coil pair comprised of two loops of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loops, and sandwiching the lower abdomen from the right and left sides with the two loops facing each other; and combining means for combining two RF signals respectively received by said first and second coil pairs in a phased-array scheme.
In the invention of the aspects described in (8)-(10), an RF coil comprises a first coil pair comprised of two loops of a geometry suited for sandwiching the lower abdomen of a human body from the anterior and posterior sides with the two loops facing each other, and a second coil pair comprised of two loops of a geometry suited for allowing the lower limbs of the human body to be inserted into the two loops, and sandwiching the lower abdomen from the right and left sides with the two loops facing each other, so that magnetic resonance signals from the prostate portion can be received with a good SNR.
In the RF coil, said two loops in said second coil pair preferably have a geometry such that the two loops are made partially close to and facing each other along a medial line of said human body so that high-sensitivity regions in the first and second coil pairs coincide with each other.
The RF coil preferably comprises a flexible substrate having a geometry suited for being fitted over the lower abdomen of the human body, for supporting circuit patterns of said first and second coil pairs, so that fitting on the human body is improved.
Therefore, the present invention can provide an RF coil, RF signal transmitting/receiving apparatus, RF signal receiving apparatus, and magnetic resonance imaging apparatus that enable proper imaging of the prostate.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.